Category: Class 12 Biology Objective Questions

Biology Multiple Choice Questions on “Flowering Plants Reproduction – Structure of Megasporangium”.

1. What is a megasporangium?
a) Pistil
b) Carpel
c) Ovule
d) Stigma
Answer: c
Clarification: An ovule is an integumented megasporangium found in spermatophytes which develops into a seed on fertilization. The cells within the megasporangium are diploid which will divide via meiosis to form 4 megaspores.

2. Angiosperm ovules are generally ______
a) pinkish
b) brownish
c) greenish
d) whitish
Answer: d
Clarification: Angiosperm ovules are generally ovoid in shape and whitish. The usually occur on the parenchymatous cushion inside the ovary which is also known as the placenta. Either singly or in a cluster.

3. Where do the ovules grow?
a) Flower
b) Gynoecium
c) Stigma
d) Placenta
Answer: d
Clarification: The ovules grow and mature on the parenchymatous cushion in the ovary, also known as the placenta. Placenta is the medium through which young ovules get nutrition. The ovules may appear singly or in a cluster.

4. What is the stalk called?
a) Carpel
b) Sepal
c) Funicle
d) Hypothalamus
Answer: c
Clarification: The ovule is stalked. The stalk or the funicle is connected to the ovary by the placenta. This point is known as the hilum. It’s through which water and nutrients go inside the ovary.

5. Depending on the configuration, 6 types of ovaries are present.
a) False
b) True
Answer: b
Clarification: Yes. There are 6 types of ovaries present according to its configuration. Orthotropous (atropous, erect), anatropous (inverted), hemitropous (half inverted), campylotropous (body curved), amphitropous (both body and embryo sac curved) and circinotropous (funiculus coiled around the ovule).

6. In a typical anatropous, the funicle is ____ with the ovary.
a) detached
b) fused
c) above
d) different
Answer: b
Clarification: In a typical anatropous, the funicle is fused with body of the ovary. It gives a longitudinal rise called the raphe. The funicle contains the vascular strands that provide nourishment to the ovary.

7. Mass of parenchymatous cells on the body of the ovary is also called ______
a) nucellus
b) meristematic cell
c) tegument
d) ovule
Answer: a
Clarification: The mass of parenchymatous cells are also known as the Nucellus. It maybe massive (crassinucellate ovule) or thin (tenuinucellate ovule). Its surrounded by one or more teguments.

8. What is ategmic?
a) Presence of 1 tegument
b) Presence of 3 teguments
c) Absence of integuments
d) Presence of 2 teguments
Answer: c
Clarification: Ategmic means the absence of integuments. Integuments are a natural outer, protective layer. Just like skin in animals, integument in plants is thin and layered.

9. Passage at one end of the ovary is called as _______
a) micropyle
b) funicle
c) chalaza
d) hilum
Answer: a
Clarification: Passage or pore present at the end of the ovary is called a micropyle. It is a small opening through which water, air, nutrients, etc. go. This pore or passage is left by integuments.

10. Origin of integuments are _____
a) funicle
b) hilum
c) micropyle
d) chalaza
Answer: d
Clarification: Chalaza is the origin of the integuments or also known as the point where the nucellus attaches itself to the integument. They are usually present on the opposite sides of the ovule (opposite to the micropyle).

Biology Multiple Choice Questions on “Human Reproduction – Structure of a Mammary Gland”.

1. What kind of tissue is the mammary gland mainly made of?
a) Adipose tissue
b) Glandular tissue
c) Epithelial tissue
d) Connective tissue
Answer: b
Clarification: A functional mammary gland is distinctive of all female mammals. The mammary glands are paired structures (breasts) that contains the glandular tissue and variable amounts of fat.

2. Glandular tissues contain _____ at the ends.
a) alveoli
b) bronchioles
c) ampulla
d) lobule
Answer: a
Clarification: The mammary glands are made of glandular tissue. The glandular tissue of each breast is divided into 15-20 mammary lobes containing clusters of cells called alveoli.

3. What do the alveoli secrete?
a) Bile
b) Hemoglobin
c) Milk
d) Sweat
Answer: c
Clarification: The cells of alveoli secrete milk, which is stored in the cavities (lumens) of alveoli. Bile is secreted by the liver that helps digest lipids. Sweat is secreted by the sweat glands to maintain body temperature.

4. What does the alveoli open into?
a) Mammary glands
b) Mammary tubules
c) Mammary ducts
d) Glandular tissue
Answer: b
Clarification: The alveoli open into mammary tubules. The tubules of each lobe join to form a mammary duct. Breasts are made up of glandular tissue.

5. Mammary ducts join and form a wider mammary ______
a) ducts
b) tubules
c) ampulla
d) tissue
Answer: c
Clarification: The alveoli opens into mammary tubules. The tubules of each lobe join to form a mammary duct. Several mammary ducts join to form a wider mammary ampulla which is connected to lactiferous duct through which milk is sucked out.

6. Mother’s milk doesn’t have any antibodies.
a) False
b) True
Answer: a
Clarification: Mother’s milk provides postnatal nourishment for the baby and provides it with basic immunity through antibodies. Immunoglobulin A is found the most in the milk.

7. Yellow fluid that appears at the earliest stage of breast feeding is called __________
a) bile
b) milk
c) cholesterol
d) colostrum
Answer: d
Clarification: Colostrum is the yellow fluid that appears at the beginning of breast feeding. It is highly nutritious for the baby as that is the only thing that provides protection for the baby (rich in antibodies).

8. Production of milk is called _________
a) Lactation
b) Galactorrhea
c) Lactorrhea
d) Galactation
Answer: a
Clarification: Lactation occurs in females only when they’ve gestated a foetus. In some cases lactorrhea also know as galactorrhea is the occasional production of milk without any gestation.

9. Contractions of the myoepithelial cells eject milk.
a) False
b) True
Answer: b
Clarification: Myoepithelial cells surround the alveoli. Contractions of these cells push the milk through the ducts and out through the nipple to feed the infant.

10. What happens after the weaning of an infant?
a) Galactorrhea
b) Lactorrhea
c) Production of milk continues
d) Involution
Answer: d
Clarification: After the weaning of an infant, the process of lactation stops and the process of apoptosis begins. This is the controlled death of the mammary cells which eventually brings back the glands to its puberty stage.

Biology Multiple Choice Questions on “Reproductive Health – Intrauterine Devices”.

1. What methods are inserted into the uterus through the vagina to prevent pregnancy?
a) Natural methods
b) Barrier methods
c) Oral methods
d) Intrauterine methods
Answer: d
Clarification: Intrauterine devices are inserted into the uterus through the vagina. Expert doctors do this. It is a contraceptive measure.

2. Intrauterine methods exist only for females.
a) True
b) False
Answer: a
Clarification: Intrauterine methods are designed to be inserted into uterus through vagina. These exist only for females. There is no similar counterpart for males because the act of fertilization occurs in the female genital tract.

3. IUDs stand for _______
a) Intra Uterine Devices
b) Inter Uterine Devices
c) Intra Uterine Diseases
d) Inter Uterine Diseases
Answer: a
Clarification: IUDs stand for Intra Uterine Devices. These are designed to be inserted through the vagina into the uterus.

4. Which of the following is a non-medicated IUD?
a) Lippes loop
b) Cu7
c) Multiload 375
d) Progestasert
Answer: a
Clarification: Lippes loop is a non-medicated IUD. It is made of an inert plastic material and can be used for longterm use.

5. Which of the following is not a copper releasing IUD?
a) Cu7
b) CuT
c) LNG-20
d) Multiload 375
Answer: c
Clarification: The copper releasing IUDs include Cu7, CuT, and Multiload 375. LNG-20 instead releases progestin, which is a hormone.

6. Which of the following IUDs work by releasing hormone?
a) Lippes loop
b) Cu7
c) Multiload 375
d) Progestasert
Answer: d
Clarification: Proestasert is an IUD. It works by releasing the hormone progesterone. This prevents pregnancy and hence acts as a contraceptive measure.

7. LNG-20 is an IUD, hence releases Cu ions to terminate pregnancy.
a) True
b) False
Answer: b
Clarification: LNG-20 is an IUD. However, not all IUDs released Cu ions. LNG-20 belongs to the class of IUDs that release hormones. LNG-20 causes the release of the hormone progestin in the uterine cavity.

8. How do IUDs prevent pregnancy?
a) By preventing mixing of vaginal and seminal fluids
b) By increasing phagocytosis of sperms
c) By increasing phagocytosis of eggs
d) By preventing the release of egg
Answer: b
Clarification: IUDs are intrauterine devices. They do not act as a barrier between vaginal and seminal fluids. Also, they do not affect the ovary or the egg. They work by enhancing the phagocytosis of sperms and thus reducing the probability of sperm entering the fallopian tube to fertilize the egg.

9. How do Cu ions in copper releasing IUDs prevent fertilization?
a) By reducing the motility of the sperms
b) By increasing the motility of the sperms
c) By causing the females to expel out the sperms
d) By causing the lysis of sperms
Answer: a
Clarification: Copper releasing IUDs include Cu7, CuT, and Multiload 375. These work by dampening the motility of the sperms. This reduces the ability of sperm to cross the barriers of the uterus before reaching the fallopian tube and thus prevents fertilization and pregnancy.

10. What is the unique feature of hormone-releasing IUDs?
a) Causing lysis of sperms
b) Increasing the release of sperms by male
c) Rendering the uterus unsuitable for the fertilized egg to implant
d) Closing of vagina
Answer: c
Clarification: The hormone-releasing IUDs are very strong and have fewer side-effects. These stimulate the body’s mechanisms to prevent fertilization. They render the cervix hostile for sperms and also make the uterus not suitable for the blastocyst to the implant. Thus, even if fertilization occurs, the chances of it leading to pregnancy are almost nil.

Biology Multiple Choice Questions on “Inheritance Principles – Co-Dominance”.

1. In what mode of inheritance, the F1 progeny exhibit characteristics of both the parents?
a) Complete dominance
b) Incomplete dominance
c) Codominance
d) Multiple allelism
Answer: c
Clarification: Codominance refers to the equal likelihood of both alleles expressing. Thus, the progeny resembles both the parents.

2. Which of the following is an instance of codominance?
a) Flower color in garden peas
b) Flower color in snapdragon
c) Blood grouping in humans
d) Pod color in garden peas
Answer: c
Clarification: The ABO blood grouping in humans is an instance of codominance. Here the lack of both A and B alleles produces a new phenotype: The O blood group.

3. ABO blood grouping in humans is an instance of ___________
a) complete dominance
b) incomplete dominance
c) codominance
d) pseudoscience
Answer: c
Clarification: Codominance refers to the production of a new phenotype when both factors that give opposing traits are present. This is observed in ABO blood grouping in humans.

4. The ABO blood groups are determined by ______ present on RBCs.
a) proteins
b) DNA
c) RNA
d) carbohydrates
Answer: d
Clarification: The ABO blood group is determined by the antigens present on the RBCs of a human. These antigens are sugar polymers.

5. The I gene which encodes for the blood group is a code for a sugar polymer.
a) True
b) False
Answer: a
Clarification: The I gene is responsible for the blood group. In a complex pathway, the allele present at the locus of I gene determines the nature of the sugar polymer expressed by the RBCs. Thus indirectly, it codes for the sugar polymer.

6. Which allele of I gene does not result in the production of any sugar antigen?
a) IA
b) IB
c) IC
d) i
Answer: d
Clarification: The I gene codes for three antigens: IA, IB, and i. IA and IB code for sugar. The i allele does not code for any sugar.

7. The cattle coat color inheritance is an instance of _______
a) complete dominance
b) incomplete dominance
c) codominance
d) multiple allelism
Answer: c
Clarification: The cattle coat color is an instance of codominance. Here the coat color of the progeny of parents that have contrasting coat colors has patches. Thus, both the alleles express codominantly resulting in a new phenotype.

8. The alleles IA and IB code for the same sugar.
a) True
b) False
Answer: b
Clarification: The genes IA and IB code for sugar. However, these sugars are slightly different. These differ in few monomers.

9. Which of the following allele is dominant over i?
a) Only IA
b) Only IB
c) Both IA and IB
d) IC
Answer: d
Clarification: The gene I has only three alleles. These are IA, IB, and i. There is no allele as IC. Also, the alleles IA and IB are dominant over i as it does not produce any sugar.

10. What will be the blood group of a person who has IAIB as the genotype?
a) A
b) B
c) AB
d) O
Answer: c
Clarification: The person has two alleles IA and IB. These are codominant alleles. Thus, both of them will produce their products. Hence the person will have the blood group AB.

11. What is the ability of both IA and IB alleles to express together called?
a) Complete dominance
b) Incomplete dominance
c) Codominance
d) Multiple allelism
Answer: c
Clarification: Codominance refers to the ability of both alleles to produce an effect even when the other is present. The alleles IA and IB are two such alleles.

Biology Multiple Choice Questions on “Molecular Basis of Inheritance – DNA”.

1. Who was the first person to analyse factors?
a) Gross
b) Haeckel
c) Mendel
d) Altmann
Answer: c
Clarification: The first person to analyse and detect factors was Mendel. In fact, he was the person who gave the term factors. They were detected by following their patterns of transmission from generation to generation.

2. In which year, the mechanism for genetic inheritance reached the molecular level?
a) 1986
b) 1999
c) 1926
d) 1945
Answer: c
Clarification: The quest to determine the mechanism for genetic inheritance reached the molecular level in 1926. The nature of the genetic material was studied at that time and it was realised that DNA is the genetic material for the majority of organisms.

3. What is the full form of DNA?
a) Degenerative acid
b) Deoxyribonucleic acid
c) Deadly nucleic acid
d) Disoriented acid
Answer: b
Clarification: DNA stands for deoxyribonucleic acid. It is a genetic material known for the majority of organisms living on this planet. This substance is responsible for controlling the inheritance of traits.

4. How many types of nucleic acids are present in the living systems?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: There are two types of nucleic acids present in our living system. These two are:
i. DNA-deoxyribonucleic acid
ii. RNA-ribonucleic acid
They both can express their effects through the formation and functioning of the traits.

5. DNA is the genetic material in all the known viruses.
a) False
b) True
Answer: a
Clarification: No, DNA is not the genetic material in all the known viruses. It is the genetic material in all organisms except for some viruses, where RNA is the major genetic material like the riboviruses.

6. Which of the following is not a function of RNA?
a) Messenger
b) Catalysis
c) Adapter
d) Modifier
Answer: d
Clarification: RNA does not behave as a modifier. Instead, it functions as a messenger that carries genetic information. It also acts as an adapter for picking up amino acids and in some cases behaves as a catalytic molecule.

7. Which of the following is not a correct statement with respect to DNA?
a) It is a long polymer
b) It is found in the nucleus
c) It is a basic substance
d) First identified by Friedrich Meischer
Answer: c
Clarification: DNA is not a basic substance. Instead, it is an acidic substance. It was first identified by Friedrich Meischer in 1869. It is also known as a long polymer of deoxyribonucleotides and is found in the nucleus of the cell.

8. Which of the following is the characteristic feature of an organism?
a) Number of RNA
b) Number of protein molecules
c) Length of chromosomes
d) Length of DNA
Answer: d
Clarification: The characteristic feature of an organism is the length of its DNA. The length of the DNA is usually defined as the number of nucleotides or the number of base pairs present in it. As this substance was acidic in nature, Altmann named it as a nucleic acid.

9. How many base pairs are present in Escherichia coli?
a) 9856 bases
b) 4.6 x 10⁶ bp
c) 3.3 x 10⁹ bp
d) 10,000 bases
Answer: b
Clarification: The number of base pairs or the number of nucleotides present in the bacterium, Escherichia coli are 4.6 x 10⁶ base pairs. The number of base pairs present in human beings is 3.3 x 10⁹.

10. How many numbers of nucleotides are present in Lambda phage?
a) 48502 bp
b) 98526 bp
c) 10000 bp
d) 5326 bp
Answer: a
Clarification: The number of nucleotides or the number of bases in Lambda phage are 48502. The genetic material of Lambda phage consists of a double-stranded DNA which is linear in shape.

11. Which of the following is correct with respect to the genetic material of Φ174 bacteriophage?
a) ss DNA, linear
b) ss RNA, linear
c) ss DNA, circular
d) ds DNA, linear
Answer: c
Clarification: The genetic material of Φ174 bacteriophage is single-stranded DNA which is circular in shape. It has 5386 bases or a number of nucleotides. It is a virus that attacks on bacteria.

12. The genetic material of humans is double-stranded DNA which is circular in shape.
a) False
b) True
Answer: a
Clarification: The genetic material of humans consists of a double-stranded DNA which is linear in shape. The genetic material of the bacterium Escherichia coli is a double-stranded DNA that is circular in shape.

13. How many components are present in the basic unit of DNA?
a) One
b) Two
c) Three
d) Four
Answer: c
Clarification: There are three components in the basic unit of DNA which is also known as a nucleotide, and they are:
i. A nitrogenous base: purine or pyrimidine
ii. A pentose sugar: Deoxyribose sugar
iii. Phosphate group.

14. Which of the following statements is correct with respect to purines?
a) Purines are heterocyclic compounds
b) Purines are 7 membered structure
c) Purines are single-ring structure
d) Thymine is an example of purine
Answer: a
Clarification: Purines are a type of nitrogenous bases which are heterocyclic compounds. They are 9 membered and are double-ring structures. Nitrogen is present at the positions-1, 3, 7 and 9 of the ring. Adenine and guanine are the only two examples of purines.

15. Which of the following statement is incorrect with respect to pyrimidines?
a) Heterocyclic
b) 7 membered ring
c) Cytosine is an example of pyrimidine
d) Single-ring structure
Answer: b
Clarification: Pyrimidines are not 7 membered rings. Pyrimidines are a type of nitrogenous bases which are heterocyclic compounds with a 6 membered single-ring structure. Nitrogen is present at 1 and 3 positions of the rings. Examples of pyrimidines include thymine, uracil, and cytosine.

16. By which of the following bonds, a nitrogenous base is linked to the pentose sugar?
a) Phosphate bond
b) Ester bond
c) Peptide bond
d) N-glycosidic bond
Answer: d
Clarification: A nitrogenous base is linked to the pentose sugar by an N-glycosidic bond. As a result of this linkage, a nucleoside is formed. Purine nucleosides have 1’-9 glycosidic linkage and pyrimidine nucleosides have 1’-1 linkage.

Biology online quiz on “Hardy-Weinberg Principle-2”.

1. Which of the following does not belong to the Hardy Weinberg principle?
a) Frequency remained fixed through generations
b) Used algebraic equations
c) Allele frequency varies from species
d) Gene pool remains a constant
Answer: c
Clarification: Allele frequencies does not vary from species to species. In a population, the frequency always remains fixed or constant according to Hardy Weinberg principle. The alleles and total genes in any population remain constant and hence stable.

2. It is known that the total sum of all the frequencies of the allele is _____
a) one
b) two
c) three
d) four
Answer: a
Clarification: According to Hardy Weinberg principle, the total sum of all the frequencies of the allele is one. It shows that the gene pool remains the same or constant, i.e. one. Hence, it can be also termed as genetic equilibrium.

3. Which of the following represents the Hardy Weinberg equation?
a) p² + q² = 1
b) p² + 2pq + q² = 1
c) p² + q² = 0
d) (p² + q²)² = 1
Answer: b
Clarification: The Hardy Weinberg equation is p² + 2pq + q² = 1. Here, p² denotes the allele of AA and q² denotes the allele aa. This shows that p, q, and A, a are related in multiplication. So, 2pq represent Aa.

4. The notation p and q of the Hardy Weinberg equation represent ________ of a diploid organism.
a) frequency of allele p
b) frequency of only allele A
c) frequency of the only allele a
d) frequency of allele A and a
Answer: d
Clarification: Individual frequencies can be represented as p and q. But for a diploid organism, p and q explain the frequency of allele A and allele a. p² represents AA whereas q² represent aa.

5. The difference in frequency indicates the extent of evolutionary change.
a) True
b) False
Answer: a
Clarification: It is a correct statement as allele frequency is the main trigger to evolution. When the frequency changes in a population either due to migration or other factors, this results in evolutionary change.

6. How many factors affect the Hardy Weinberg principle?
a) Six
b) Four
c) Seven
d) Five
Answer: d
Clarification: Hardy Weinberg stated that there are six factors affecting this principle. They are Gene migration or gene flow, genetic drift, mutation, genetic recombination, and natural selection. Each factor plays a major role in evolution.

7. Which of the following does not belong to factors affecting the Hardy Weinberg principle?
a) Gene migration
b) Genetic drift
c) Genetic drop
d) Mutation
Answer: c
Clarification: There are six factors affecting this principle. Among the factors, the genetic drop is not included in them. They only include Gene migration or gene flow, genetic drift, mutation, genetic recombination, and natural selection.

8. The process when some species migrate from the original to a new place, which in turn changes the allele frequency is called ______
a) Gene drift
b) Gene migration
c) Gene travel
d) Genetic recombination
Answer: b
Clarification: Gene migration or gene flow occurs when some species migrate from original to a new place. This changes the allele frequency in the old as well as a new place. So, new genes or alleles are being added to the new population and removed from the old one.

9. Gene drift occurs when gene migration occurs ______
a) by chance
b) spontaneously
c) slowly
d) due to disaster
Answer: a
Clarification: Gene flow occurs when gene migration occurs many or multiple times. When this occurs by a chance, a process called gene drift occurs. It cannot occur spontaneously, slowly or due to a disaster.

10. Which is the correct statement regarding Founder effect?
a) Named after the scientist John Founder
b) No large change in frequency
c) The old population become founders
d) Formation of new species
Answer: d
Clarification: Some species travel to new places. This changes the allele frequency totally and makes them different species. So, the original species that migrated become founders. Hence the name Founder effect.

11. What results in the formation of new phenotypes?
a) Pre-existing helpful mutations
b) Post-existing helpful mutations
c) Pre-existing disadvantageous mutations
d) Post-existing advantageous mutations
Answer: a
Clarification: According to microbial experiments, pre-existing helpful of advantageous mutations results in the formation of new phenotypes. This finally results in a process called Speciation. Mutation also has a relation with creating new phenotypes.

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